To cope with a busy pace of modern life, various mobile devices occupying less space and easy to carry are developed. Taking a smart phone as an example, the smart phone not only has various functions of a conventional communication device, but also allows a user to write documents, send and receive emails, browse websites, or use instant messaging software through software inbuilt therein. Namely, the mobile device is not only used for making phone calls, but is also used to provide diversified functions as that does of a smaller personal computer, and with development of wireless network techniques, usage of theses functions is not limited by time and space, and for the modern people demanding efficiency, such device has become one of independent tools in daily life.
However, the mobile device requires features of lightness, slimness, shortness, and smallness, and therefore a size of a screen disposed on the mobile device is limited. The reduction of screen size may limit batches of information capable of being displayed on the screen. As a result, images with high resolution can only be displayed with limited display resolution, and details of the images are lost. Even though a user may magnify the displayed image by using a zoom-in function, the view of image is reduced to a partial image. Therefore, the requirements for resolution and completeness of the image cannot be simultaneously satisfied.